Implantable medical devices (IMDs) are utilized in a variety of medical applications for sensing and deriving physiologic parameters within the body. In cardiac rhythm management (CRM) systems used to monitor the status of a patient's heart, for example, an implantable sensor may sense various hemodynamic parameters within the atria and/or ventricles of the heart, or within the vessels leading into or from the heart. In one such system, for example, a remote pressure sensor implanted within one of the pulmonary arteries can be used to sense arterial blood pressure data.
The sensed hemodynamic data obtained from such devices can be used to derive information such as heart rate, cardiac output, and stroke volume. In some systems, the sensed hemodynamic data can be wirelessly transmitted to another implant within the body and/or to an external device for further analysis, often in conjunction with other sensed parameters. An example device adapted to sense arterial pressure measurements within a pulmonary artery and acoustically communicate those measurements to another implant or to an external device is described in U.S. Pat. No. 7,024,248, entitled “Systems and Methods For Communicating With Implantable Devices,” the contents of which are incorporated herein by reference in its entirety for all purposes.
The interpretation and analysis of sensed blood pressure data may be difficult in some circumstances without correlating the data with the patient's cardiac rhythm. In diagnosing events or conditions such as arrhythmia or pulsus alternans, for example, it may be necessary to correlate the rhythm associated with the sensed blood pressure data with electrical activity occurring within the heart in order to accurately interpret the blood pressure data and diagnose the presence of the event or condition.